Terahertz Reflection Spectroscopy of Aqueous NaCl and LiCl Solutions
We present spectroscopic measurements of the full dielectric function of aqueous solutions of sodium chloride and lithium chloride at concentrations approaching their solubility limits at room temperature. We find that the dielectric properties of the two salts are rather different at THz frequencies. Whereas both the real and imaginary part of the permittivity of NaCl increases with concentration, we see that the imaginary part of the permittivity of LiCl (related to the absorption) decreases with increasing salt concentration. We relate these changes to the behavior of slow and fast Debye relaxation processes in the solutions.
KeywordsTerahertz time-domain spectroscopy Electrolyte solution Debye relaxation Dielectric function
- 4.D. A. Turton, J. Hunger, A. Stoppa, G. Hefter, A. Thoman, M. Walther et al., “Dynamics of imidazolium ionic liquids from a combined dielectric relaxation and Optical Kerr Effect study: Evidence for mesoscopic aggregation,” Journal of the American Chemical Society 131, 11140–11146 (2009).Google Scholar
- 7.U. Møller, D. G. Cooke, K. Tanaka, and P. Uhd Jepsen, “Terahertz reflection spectroscopy of Debye relaxation in polar liquids,” Journal of the Optical Society of America B 19, A113–A125 (2009).Google Scholar
- 24.M. Heyden, E. Brundermann, U. Heugen, G. Niehues, D. M. Leitner, and M. Havenith, “Long-range influence of carbohydrates on the solvation dynamics of water - Answers from terahertz absorption measurements and molecular modeling simulations,” Journal of the American Chemical Society 130, 5773–5779 (2008).CrossRefGoogle Scholar